Cost per mile:
the only number
that matters.

Most owner-operators know what they earn per mile. Almost none of them know what they actually spend per mile. The gap between those two numbers is your real profit — and it's almost always smaller than the rate sheet suggests.

This guide explains the four cost categories every trucker needs to track, walks through a working example with real numbers, and shows what to do with the result once you have it.

Why CPM is the only number that matters.

A driver hauls a $3,400 load 1,200 miles and feels good. The math: $2.83 per mile gross. But after fuel ($720), the truck payment for those days ($340), insurance allocated to those miles ($120), tolls ($95), maintenance reserve ($240), and per diem ($240), the actual profit is $1,645 — or $1.37 per mile. If the driver's personal CPM target was $2.00, this load was unprofitable, even though the rate sheet said $2.83.

Without CPM, you're flying blind. You take loads that look great and lose money. You turn down loads that look mediocre and would have been your best-margin runs of the year. Knowing your CPM is what separates an owner-operator who builds equity from one who's slowly going broke at $2.50 a mile.

The four cost buckets.

Every dollar you spend running the truck falls into one of four categories. Each one needs its own tracking method.

1. Variable costs (per-mile)

These scale directly with miles driven:

• Fuel — your single biggest variable cost. Track gallons and price for every fill.
• Tires — typically replaced every 100,000–200,000 miles. Spread the cost as a per-mile reserve.
• Routine maintenance — oil changes, brakes, filters. Set a per-mile reserve based on annual averages.
• DEF — usually 2–3% of fuel cost.
• Tolls — variable by route, but real money on East Coast lanes.

2. Fixed costs (per-day or per-month)

These hit whether you drive or not:

• Truck payment / lease
• Trailer payment (if applicable)
• Insurance — primary, cargo, occupational accident
• Permits and licensing — IFTA, IRP, UCR, state permits
• ELD subscription
• Phone, dispatch, factoring fees
• Parking when not at home base

To convert these to a per-mile cost, divide your monthly fixed cost by your average monthly miles. If your fixed costs are $5,200/month and you average 10,000 miles, your fixed CPM is $0.52.

3. Maintenance reserve (the bucket nobody funds)

This is the cost most drivers miss until something breaks. A turbocharger goes out at 600,000 miles. A clutch at 700,000. An overhaul at 1,000,000. None of these happen on schedule. You need a per-mile reserve set aside in a separate account so the cash is there when the part fails.

Industry rule of thumb: $0.10–$0.15 per mile set aside for major repairs. On 120,000 annual miles, that's $12,000–$18,000 a year going into the reserve. It feels like a lot until the day a transmission costs you $14,000.

4. Owner draw (your paycheck)

Most drivers forget to count themselves as a line item. If you don't include your own pay in the CPM calculation, you'll consistently take loads that don't actually pay you — they just keep the truck running.

Decide what you need to take home each year. Divide by miles. That's your driver-pay CPM.

The full calculation — a real example.

Let's say you run 120,000 miles a year. Here's the breakdown:

Your CPM is $1.74. That means every load that pays under $1.74/mile is losing you money. Loads at $2.10–$2.50 are normal-margin. Loads above $2.50 are the ones that build wealth.

What CPM does for your business.

Once you know your number, three things change:

You stop taking bad loads. A $2.20/mile load looks fine until you realize your CPM is $2.10 — that's a 4.5% margin. A $2.50/mile load on the same lane is suddenly 16% margin. Same dispatcher, same lane, but one load makes you $360 and the other makes you $1,300 over 1,000 miles.

You negotiate from data. When a broker offers $2.30, "I need $2.65 to make this work" is a vastly stronger position than "I want more money." Brokers know which drivers know their numbers.

You see which fixed costs to cut first. If your insurance is $0.18/mile but the industry average is $0.12, that's a $7,200/year leak. CPM exposes the leaks.

How to actually track this.

You need three things:

1. A trip log with miles per trip (and per state if you file IFTA)
2. A fuel log with gallons, price, and total cost per fill
3. A monthly summary that aggregates everything and divides by miles

That's it. The free Trucking Mileage Log covers the first two and gives you a basic monthly summary. The full version adds the income/expense tracker that produces a proper CPM dashboard with profit-per-mile by trip and by month.